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                            <b>1.2.</b>
                        
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                            <b>2.2.</b>
                        
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                        群组选择器
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                        属性选择器
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                        伪类选择器
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                        常用样式分类
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                        利用border画三角形
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                        对话框旁边的小角制作
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                        光标和placeholder颜色
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                        移动端相关
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                        JavaScript
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                        JavaScript的严格模式
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                        变量
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                        Math
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                            <b>4.4.</b>
                        
                        运算符
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                            <b>4.5.</b>
                        
                        语句
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                        函数
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                        定时器
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                        DOM操作
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                        查找
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                        增加
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                        移除
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                        在HTML中使用JavaScript
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                        JavaScript控制样式和属性
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                        JSON相关
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                        <h1 id="&#x8BED;&#x53E5;&#x5224;&#x65AD;">&#x8BED;&#x53E5;&#x5224;&#x65AD;</h1>
<h2 id="if&#x8BED;&#x53E5;">if&#x8BED;&#x53E5;</h2>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> score = prompt(<span class="hljs-string">&quot;&#x8BF7;&#x8F93;&#x5165;&#x6210;&#x7EE9;&quot;</span>,<span class="hljs-string">&quot;0&quot;</span>);
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<h2 id="switch&#x8BED;&#x53E5;">switch&#x8BED;&#x53E5;</h2>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> score = prompt(<span class="hljs-string">&quot;&#x8BF7;&#x8F93;&#x5165;&#x6210;&#x7EE9;&quot;</span>,<span class="hljs-string">&quot;0&quot;</span>);
score = <span class="hljs-built_in">parseFloat</span>(score);

<span class="hljs-keyword">switch</span>(<span class="hljs-literal">true</span>){

<span class="hljs-comment">//switch&#x5C0F;&#x62EC;&#x53F7;&#x91CC;&#x7684;&#x53D8;&#x91CF;&#x5FC5;&#x987B;&#x4E0E;case&#x5C0F;&#x62EC;&#x53F7;&#x7684;&#x7ED3;&#x679C;&#x5168;&#x7B49;&#x4E8E;&#xFF0C;&#x624D;&#x4F1A;&#x8FDB;&#x5165;&#x8BE5;case</span>

    <span class="hljs-keyword">case</span> (score&gt;=<span class="hljs-number">0</span>&amp;&amp;score&lt;<span class="hljs-number">60</span>):{
        alert(<span class="hljs-string">&quot;&#x4E0D;&#x53CA;&#x683C;&quot;</span>);
        <span class="hljs-keyword">break</span>;
    }
    <span class="hljs-keyword">case</span> (score&gt;=<span class="hljs-number">60</span>&amp;&amp;score&lt;<span class="hljs-number">80</span>):{
        alert(<span class="hljs-string">&quot;&#x826F;&quot;</span>);
        <span class="hljs-keyword">break</span>;
    }
    <span class="hljs-keyword">case</span> (score&gt;=<span class="hljs-number">80</span>&amp;&amp;score&lt;=<span class="hljs-number">95</span>):
    <span class="hljs-keyword">case</span> (score&gt;<span class="hljs-number">95</span>&amp;&amp;score&lt;=<span class="hljs-number">100</span>):{
        alert(<span class="hljs-string">&quot;&#x4F18;&quot;</span>);
        <span class="hljs-keyword">break</span>;
    }
    <span class="hljs-keyword">default</span>:{
    <span class="hljs-comment">//&#x5982;&#x679C;&#x524D;&#x9762;&#x7684;&#x5206;&#x652F;&#x90FD;&#x4E0D;&#x7B26;&#x5408;&#x6216;&#x6CA1;&#x6709;&#x8DF3;&#x51FA;switch&#xFF0C;&#x90A3;&#x4E48;&#x90FD;&#x4F1A;&#x8D70;&#x8FDB;default</span>
        alert(<span class="hljs-string">&quot;&#x4E0D;&#x5408;&#x6CD5;&quot;</span>);
        <span class="hljs-keyword">break</span>;
    }
}
</code></pre>
<h2 id="while&#x4E0E;do-while&#x8BED;&#x53E5;">while&#x4E0E;do while&#x8BED;&#x53E5;</h2>
<pre><code class="lang-javascript"><span class="hljs-comment">//do while</span>
<span class="hljs-keyword">var</span> j = <span class="hljs-number">0</span>;
<span class="hljs-keyword">do</span>{
    <span class="hljs-built_in">console</span>.log(j);
    j++;
}<span class="hljs-keyword">while</span>(j&lt;<span class="hljs-number">10</span>)

<span class="hljs-comment">//while</span>
<span class="hljs-keyword">while</span>(j&lt;<span class="hljs-number">10</span>){
    <span class="hljs-built_in">console</span>.log(j);
    j++;
}
</code></pre>
<h2 id="for-in-&#x8BED;&#x53E5;">for in &#x8BED;&#x53E5;</h2>
<p>&#x5FAA;&#x73AF;&#x53EF;&#x679A;&#x4E3E;&#x5C5E;&#x6027;&#xFF0C;<strong>&#x4E0B;&#x9762;&#x7684;k&#x4E3A;&#x7D22;&#x5F15;&#x503C;&#xFF08;&#x6216;&#x4E0B;&#x6807;&#xFF09;</strong></p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> arr = [<span class="hljs-number">0</span>,<span class="hljs-number">2</span>,<span class="hljs-number">4</span>,<span class="hljs-number">5</span>,<span class="hljs-number">6</span>,<span class="hljs-number">8</span>,<span class="hljs-number">7</span>,<span class="hljs-number">4</span>,<span class="hljs-number">9</span>,<span class="hljs-number">2</span>,<span class="hljs-number">5</span>,<span class="hljs-number">5</span>];

<span class="hljs-keyword">for</span>(<span class="hljs-keyword">var</span> k <span class="hljs-keyword">in</span> arr){

    <span class="hljs-comment">//k&#x4E3A;&#x5B57;&#x7B26;&#x4E32;</span>
    <span class="hljs-keyword">if</span>(<span class="hljs-built_in">parseInt</span>(k)===<span class="hljs-number">3</span>){
        <span class="hljs-keyword">break</span>;
    }
    <span class="hljs-built_in">console</span>.log(arr[k]);
    <span class="hljs-comment">//&#x6309;&#x987A;&#x5E8F;&#x904D;&#x5386;&#x4E00;&#x904D;&#x6570;&#x503C;</span>
}

<span class="hljs-keyword">var</span> obj = {
    <span class="hljs-string">&quot;name&quot;</span>:<span class="hljs-string">&quot;bgg&quot;</span>,
    age:<span class="hljs-number">18</span>,
    tall:<span class="hljs-number">180</span>
}
<span class="hljs-keyword">for</span>(<span class="hljs-keyword">var</span> k <span class="hljs-keyword">in</span> obj){
    <span class="hljs-built_in">console</span>.log(k);
}
<span class="hljs-comment">//name age tall</span>
</code></pre>
<h2 id="for-of-&#x8BED;&#x53E5;">for of &#x8BED;&#x53E5;</h2>
<p>&#x53EF;&#x4EE5;&#x4F7F;&#x7528;&#x7684;for...of...&#x7684;&#x7C7B;&#x578B;</p>
<ul>
<li>Array</li>
<li>Map</li>
<li>Set</li>
<li>String</li>
<li>TypedArray</li>
<li>&#x51FD;&#x6570;&#x7684;arguments&#x5BF9;&#x8C61;</li>
<li>NodeList&#x5BF9;&#x8C61;</li>
</ul>
<p>&#x5FAA;&#x73AF;&#x53EF;&#x679A;&#x4E3E;&#x5C5E;&#x6027;&#x5BF9;&#x5E94;&#x7684;&#x503C;&#xFF0C;<strong>&#x4E0B;&#x9762;&#x7684;k&#x4E3A;&#x5C5E;&#x6027;&#x503C;</strong></p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> arr = [<span class="hljs-number">0</span>,<span class="hljs-number">2</span>,<span class="hljs-number">4</span>,<span class="hljs-number">5</span>,<span class="hljs-number">6</span>,<span class="hljs-number">8</span>,<span class="hljs-number">7</span>,<span class="hljs-number">4</span>,<span class="hljs-number">9</span>,<span class="hljs-number">2</span>,<span class="hljs-number">5</span>,<span class="hljs-number">5</span>];

<span class="hljs-keyword">for</span>(<span class="hljs-keyword">var</span> k <span class="hljs-keyword">of</span> arr){
    <span class="hljs-built_in">console</span>.log(k);
    <span class="hljs-comment">//&#x6309;&#x987A;&#x5E8F;&#x904D;&#x5386;&#x4E00;&#x904D;&#x6570;&#x503C;</span>
}
</code></pre>
<h2 id="try-catch-finally">try catch finally</h2>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> bgg1 = <span class="hljs-string">&quot;finally&quot;</span>;
<span class="hljs-keyword">try</span>{
    <span class="hljs-built_in">console</span>.log(bgg);
}
<span class="hljs-keyword">catch</span>(e){
<span class="hljs-comment">//&#x6709;&#x62A5;&#x9519;&#x5219;&#x6293;&#x53D6;&#x4F4F;&#x9519;&#x8BEF;&#xFF0C;&#x65E0;&#x9519;&#x7565;&#x8FC7;</span>
    <span class="hljs-built_in">console</span>.log(e);
}
<span class="hljs-keyword">finally</span>{
<span class="hljs-comment">//&#x65E0;&#x8BBA;&#x6709;&#x65E0;&#x9519;&#x8BEF;&#xFF0C;&#x90FD;&#x4F1A;&#x6267;&#x884C;</span>
    <span class="hljs-built_in">console</span>.log(bgg1);
}
<span class="hljs-comment">//&#x4E0B;&#x9762;&#x7684;&#x4EE3;&#x7801;&#x80FD;&#x6B63;&#x5E38;&#x7684;&#x8FD0;&#x884C;</span>
<span class="hljs-built_in">console</span>.log(<span class="hljs-number">123</span>);
</code></pre>
<h2 id="eval">eval</h2>
<pre><code class="lang-javascript">alert(aa);
<span class="hljs-keyword">var</span> aa =<span class="hljs-number">100</span>; <span class="hljs-comment">//&#x4E0D;&#x6CE8;&#x91CA;&#x5219;&#x5F39;&#x51FA;undefined&#xFF0C;&#x6CE8;&#x91CA;&#x5219;&#x62A5;&#x9519;</span>
<span class="hljs-built_in">eval</span>(<span class="hljs-string">&quot;var aa = 100;&quot;</span>);
<span class="hljs-comment">//eval&#x4E2D;&#x7684;var&#x5E76;&#x6CA1;&#x6709;&#x88AB;&#x201C;&#x63D0;&#x5347;&#x201D;</span>
</code></pre>
<h2 id="&#x6807;&#x7B7E;&#x540D;">&#x6807;&#x7B7E;&#x540D;</h2>
<pre><code class="lang-javascript">
<span class="hljs-keyword">var</span> arr1 = [<span class="hljs-number">0</span>,<span class="hljs-number">1</span>,<span class="hljs-number">2</span>,<span class="hljs-number">3</span>,<span class="hljs-number">4</span>,<span class="hljs-number">5</span>,<span class="hljs-number">6</span>,<span class="hljs-number">7</span>,<span class="hljs-number">8</span>,<span class="hljs-number">9</span>];
<span class="hljs-keyword">var</span> arr2 = [<span class="hljs-number">0</span>,<span class="hljs-number">1</span>,<span class="hljs-number">2</span>,<span class="hljs-number">3</span>,<span class="hljs-number">4</span>,<span class="hljs-number">5</span>,<span class="hljs-number">6</span>,<span class="hljs-number">7</span>,<span class="hljs-number">8</span>,<span class="hljs-number">9</span>];

loop1:<span class="hljs-keyword">for</span>(<span class="hljs-keyword">var</span> k <span class="hljs-keyword">in</span> arr1){
<span class="hljs-comment">//&#x6807;&#x7B7E;&#x540D;</span>
    loop2:<span class="hljs-keyword">for</span>(<span class="hljs-keyword">var</span> j <span class="hljs-keyword">in</span> arr2){
        <span class="hljs-keyword">if</span>(arr2[j]==<span class="hljs-number">4</span>){
<span class="hljs-comment">//            break;</span>
<span class="hljs-comment">//            continue;</span>
            <span class="hljs-keyword">break</span> loop2;
<span class="hljs-comment">//            continue loop2;</span>
<span class="hljs-comment">//            break loop1;</span>
<span class="hljs-comment">//            continue loop1;</span>
        }

<span class="hljs-comment">//        debugger;</span>
<span class="hljs-comment">//        &#x81EA;&#x52A8;&#x6253;&#x65AD;&#x5F53;&#x524D;&#xFF0C;&#x53EF;&#x4E00;&#x6B21;&#x4E00;&#x6B21;&#x7684;&#x624B;&#x52A8;&#x63A8;&#x8FDB;</span>
        <span class="hljs-built_in">console</span>.log(arr2[j]);
    }
}
</code></pre>
<h2 id="&#x66F4;&#x51C6;&#x786E;&#x7684;&#x67E5;&#x627E;&#x7C7B;&#x578B;&#x7684;&#x65B9;&#x6CD5;">&#x66F4;&#x51C6;&#x786E;&#x7684;&#x67E5;&#x627E;&#x7C7B;&#x578B;&#x7684;&#x65B9;&#x6CD5;</h2>
<pre><code class="lang-javascript"><span class="hljs-built_in">Object</span>.prototype.toString.call(arr).slice(<span class="hljs-number">8</span>,-<span class="hljs-number">1</span>).toLowerCase();

<span class="hljs-comment">//slice&#x526A;&#x5207;&#x7247;&#x6BB5;</span>
<span class="hljs-comment">//String.toLowerCase() &#x8F6C;&#x4E3A;&#x5C0F;&#x5199;</span>
<span class="hljs-comment">//String.toUpperCase() &#x8F6C;&#x4E3A;&#x5927;&#x5199;</span>
</code></pre>
<h2 id="&#x7C7B;&#x578B;&#x4E4B;&#x95F4;&#x7684;&#x8F6C;&#x6362;">&#x7C7B;&#x578B;&#x4E4B;&#x95F4;&#x7684;&#x8F6C;&#x6362;</h2>
<h3 id="1&#x6570;&#x503C;&#x8F6C;&#x4E3A;&#x5B57;&#x7B26;&#x4E32;">1.&#x6570;&#x503C;&#x8F6C;&#x4E3A;&#x5B57;&#x7B26;&#x4E32;</h3>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> i = <span class="hljs-number">11</span>;
i = i.toString();
</code></pre>
<h3 id="2&#x5B57;&#x7B26;&#x4E32;&#x8F6C;&#x4E3A;&#x6570;&#x5B57;">2.&#x5B57;&#x7B26;&#x4E32;&#x8F6C;&#x4E3A;&#x6570;&#x5B57;</h3>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> j = <span class="hljs-string">&quot;123&quot;</span>;

<span class="hljs-comment">//parseInt  &#x8F6C;&#x4E3A;&#x6574;&#x578B;&#x6570;&#x503C;&#xFF1B;</span>
j = <span class="hljs-built_in">parseInt</span>(j);

<span class="hljs-comment">//parseFloat  &#x8F6C;&#x4E3A;&#x6D6E;&#x70B9;&#x578B;&#x6570;&#x503C;&#x3002;</span>
j = <span class="hljs-built_in">parseFloat</span>(j);

<span class="hljs-comment">//parseInt(a,b) a&#x4EE3;&#x8868;&#x6570;&#x503C;&#xFF0C;b&#x4EE3;&#x8868;&#x8F6C;&#x6362;&#x7684;&#x8FDB;&#x5236;</span>
z = <span class="hljs-built_in">parseInt</span>(<span class="hljs-number">0xff</span>,<span class="hljs-number">10</span>);
</code></pre>

                    
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